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Li H, Seessle J, Staffer S, Tuma-Kellner S, Poschet G, Herrmann T, Chamulitrat W. FATP4 deletion in liver cells induces elevation of extracellular lipids via metabolic channeling towards triglycerides and lipolysis. Biochem Biophys Res Commun 2023; 687:149161. [PMID: 37931418 DOI: 10.1016/j.bbrc.2023.149161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 10/13/2023] [Accepted: 10/26/2023] [Indexed: 11/08/2023]
Abstract
Evidence from mice with global deletion of fatty-acid transport protein4 (FATP4) indicates its role on β-oxidation and triglycerides (TG) metabolism. We reported that plasma glycerol and free fatty acids (FA) were increased in liver-specific Fatp4 deficient (L-FATP4-/-) mice under dietary stress. We hypothesized that FATP4 may mediate hepatocellular TG lipolysis. Here, we demonstrated that L-FATP4-/- mice showed an increase in these blood lipids, liver TG, and subcutaneous fat weights. We therefore studied TG metabolism in response to oleate treatment in two experimental models using FATP4-knockout HepG2 (HepKO) cells and L-FATP4-/- hepatocytes. Both FATP4-deificient liver cells showed a significant decrease in β-oxidation products by ∼30-35% concomitant with marked upregulation of CD36, FATP2, and FATP5 as well as lipoprotein microsomal-triglyceride-transfer protein genes. By using 13C3D5-glycerol, HepKO cells displayed an increase in metabolically labelled TG species which were further increased with oleate treatment. This increase was concomitant with a step-wise elevation of TG in cells and supernatants as well as the secretion of cholesterol very low-density and high-density lipoproteins. Upon analyzing TG lipolytic enzymes, both mutant liver cells showed marked upregulated expression of hepatic lipase, while that of hormone-sensitive lipase and adipose-triglyceride lipase was downregulated. Lipolysis measured by extracellular glycerol and free FA was indeed increased in mutant cells, and this event was exacerbated by oleate treatment. Taken together, FATP4 deficiency in liver cells led to a metabolic shift from β-oxidation towards lipolysis-directed TG and lipoprotein secretion, which is in line with an association of FATP4 polymorphisms with blood lipids.
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Affiliation(s)
- Huili Li
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany; Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022, Wuhan, Hubei, China
| | - Jessica Seessle
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Simone Staffer
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Sabine Tuma-Kellner
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Gernot Poschet
- Metabolomics Core Technology Platform, Centre for Organismal Studies, University of Heidelberg, 69120, Heidelberg, Germany
| | - Thomas Herrmann
- Westkuesten Hospital, Esmarchstraße 50, 25746, Heide, Germany
| | - Walee Chamulitrat
- Department of Internal Medicine IV, University Hospital Heidelberg, 69120, Heidelberg, Germany.
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Xu P, Chen C, Zhang Y, Dzieciatkowska M, Brown BC, Zhang W, Xie T, Abdulmalik O, Song A, Tong C, Qi H, Roach R, Kellems RE, D'Alessandro A, Xia Y. Erythrocyte transglutaminase-2 combats hypoxia and chronic kidney disease by promoting oxygen delivery and carnitine homeostasis. Cell Metab 2022; 34:299-316.e6. [PMID: 35108516 DOI: 10.1016/j.cmet.2021.12.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 09/29/2021] [Accepted: 12/21/2021] [Indexed: 02/03/2023]
Abstract
Due to lack of nuclei and de novo protein synthesis, post-translational modification (PTM) is imperative for erythrocytes to regulate oxygen (O2) delivery and combat tissue hypoxia. Here, we report that erythrocyte transglutminase-2 (eTG2)-mediated PTM is essential to trigger O2 delivery by promoting bisphosphoglycerate mutase proteostasis and the Rapoport-Luebering glycolytic shunt for adaptation to hypoxia, in healthy humans ascending to high altitude and in two distinct murine models of hypoxia. In a pathological hypoxia model with chronic kidney disease (CKD), eTG2 is critical to combat renal hypoxia-induced reduction of Slc22a5 transcription and OCNT2 protein levels via HIF-1α-PPARα signaling to maintain carnitine homeostasis. Carnitine supplementation is an effective and safe therapeutic approach to counteract hypertension and progression of CKD by enhancing erythrocyte O2 delivery. Altogether, we reveal eTG2 as an erythrocyte protein stabilizer orchestrating O2 delivery and tissue adaptive metabolic reprogramming and identify carnitine-based therapy to mitigate hypoxia and CKD progression.
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Zhang Q, Liu X, Piao C, Jiao Z, Ma Y, Wang Y, Liu T, Xu J, Wang H. Effect of conditioned medium from adipose derived mesenchymal stem cells on endoplasmic reticulum stress and lipid metabolism after hepatic ischemia reperfusion injury and hepatectomy in swine. Life Sci 2022; 289:120212. [PMID: 34896163 DOI: 10.1016/j.lfs.2021.120212] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/23/2021] [Accepted: 12/01/2021] [Indexed: 02/07/2023]
Abstract
AIMS Hepatic ischemia reperfusion injury (HIRI) is associated with liver failure after liver transplantation and hepatectomy. Thus, this study aims to explore the effect of conditioned medium from adipose derived stem cells (ADSC-CM) on endoplasmic reticulum stress (ERS) and lipid metabolism after HIRI combined with hepatectomy in miniature pigs. MAIN METHODS A model of HIRI combined with hepatectomy in miniature pigs was established. The expression of ERS-related proteins and lipid metabolism related genes, as well as triglyceride (TG), total cholesterol (TC), high density lipoprotein (HDL), very low density lipoprotein (VLDL) and acetyl-CoA carboxylase 1 (ACC1) level were measured in liver tissues. KEY FINDINGS Both ADSCs and ADSC-CM could improve the damage in the ultrastructure of hepatocytes. ADSC-CM significantly decreased the protein expression of GRP78, ATF6, XBP1, p-eIF2α, ATF4, p-JNK and CHOP. Oil red O staining revealed that the degree of hepatocyte steatosis was also significantly reduced after treatment with ADSC-CM. In addition, ADSC-CM remarkably decreased TG, TC, HDL and ACC1 level in liver tissues, while enhanced VLDL content. Finally, SREBP1, SCAP, FASN, ACC1, HMGCR and HMGCS1 mRNA expression was also markedly downregulated in liver tissues. SIGNIFICANCE Injection of ADSC-CM into the hepatic parenchymal could represent a novel cell-free therapeutic approach to improve HIRI combined with hepatectomy injury. The inhibition of ERS and the improvement of lipid metabolism in the hepatocytes might be a potential mechanism used by ADSC-CM to prevent liver injury from HIRI combined with hepatectomy.
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Affiliation(s)
- Qianzhen Zhang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, PR China
| | - Xiaoning Liu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Chenxi Piao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Zhihui Jiao
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, PR China
| | - Yajun Ma
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Yue Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Tao Liu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Jiayuan Xu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Hongbin Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China.
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Simon J, Nuñez-García M, Fernández-Tussy P, Barbier-Torres L, Fernández-Ramos D, Gómez-Santos B, Buqué X, Lopitz-Otsoa F, Goikoetxea-Usandizaga N, Serrano-Macia M, Rodriguez-Agudo R, Bizkarguenaga M, Zubiete-Franco I, Gutiérrez-de Juan V, Cabrera D, Alonso C, Iruzubieta P, Romero-Gomez M, van Liempd S, Castro A, Nogueiras R, Varela-Rey M, Falcón-Pérez JM, Villa E, Crespo J, Lu SC, Mato JM, Aspichueta P, Delgado TC, Martínez-Chantar ML. Targeting Hepatic Glutaminase 1 Ameliorates Non-alcoholic Steatohepatitis by Restoring Very-Low-Density Lipoprotein Triglyceride Assembly. Cell Metab 2020; 31:605-622.e10. [PMID: 32084378 PMCID: PMC7259377 DOI: 10.1016/j.cmet.2020.01.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 02/05/2019] [Accepted: 01/28/2020] [Indexed: 12/21/2022]
Abstract
Non-alcoholic steatohepatitis (NASH) is characterized by the accumulation of hepatic fat in an inflammatory/fibrotic background. Herein, we show that the hepatic high-activity glutaminase 1 isoform (GLS1) is overexpressed in NASH. Importantly, GLS1 inhibition reduces lipid content in choline and/or methionine deprivation-induced steatotic mouse primary hepatocytes, in human hepatocyte cell lines, and in NASH mouse livers. We suggest that under these circumstances, defective glutamine fueling of anaplerotic mitochondrial metabolism and concomitant reduction of oxidative stress promotes a reprogramming of serine metabolism, wherein serine is shifted from the generation of the antioxidant glutathione and channeled to provide one-carbon units to regenerate the methionine cycle. The restored methionine cycle can induce phosphatidylcholine synthesis from the phosphatidylethanolamine N-methyltransferase-mediated and CDP-choline pathways as well as by base-exchange reactions between phospholipids, thereby restoring hepatic phosphatidylcholine content and very-low-density lipoprotein export. Overall, we provide evidence that hepatic GLS1 targeting is a valuable therapeutic approach in NASH.
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Affiliation(s)
- Jorge Simon
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Maitane Nuñez-García
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), 48940 Leioa, Bizkaia, Spain
| | - Pablo Fernández-Tussy
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Lucía Barbier-Torres
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - David Fernández-Ramos
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Beatriz Gómez-Santos
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), 48940 Leioa, Bizkaia, Spain
| | - Xabier Buqué
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), 48940 Leioa, Bizkaia, Spain; Biocruces Health Research Institute, 48903 Barakaldo, Bizkaia, Spain
| | - Fernando Lopitz-Otsoa
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Naroa Goikoetxea-Usandizaga
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Marina Serrano-Macia
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Rubén Rodriguez-Agudo
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Maider Bizkarguenaga
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Imanol Zubiete-Franco
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Virginia Gutiérrez-de Juan
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Diana Cabrera
- Metabolomics Platform, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | | | - Paula Iruzubieta
- Gastroenterology and Hepatology Department, Marqués de Valdecilla University Hospital, 39008 Santander, Spain; Clinical and Traslational Digestive Research Group, Instituto de Investigación Sanitaria Valdecilla (IDIVAL), 39011 Santander, Spain
| | - Manuel Romero-Gomez
- Unit for the Clinical Management of Digestive Diseases, Hospital Universitario Virgen del Rocío, CIBERehd, University of Seville, 41013 Seville, Spain
| | - Sebastiaan van Liempd
- Metabolomics Platform, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | | | - Ruben Nogueiras
- Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria, CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Galician Agency of Innovation (GAIN), Xunta de Galicia, 15782 Santiago de Compostela, Spain
| | - Marta Varela-Rey
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Juan Manuel Falcón-Pérez
- Metabolomics Platform, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Bizkaia, Spain
| | - Erica Villa
- Department of Gastroenterology, Azienda Ospedaliero-Universitaria & University of Modena and Reggio Emilia, 41121 Modena, Italy
| | - Javier Crespo
- Gastroenterology and Hepatology Department, Marqués de Valdecilla University Hospital, 39008 Santander, Spain; Clinical and Traslational Digestive Research Group, Instituto de Investigación Sanitaria Valdecilla (IDIVAL), 39011 Santander, Spain
| | - Shelly C Lu
- Division of Digestive and Liver Diseases, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, United States
| | - Jose M Mato
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Patricia Aspichueta
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), 48940 Leioa, Bizkaia, Spain; Biocruces Health Research Institute, 48903 Barakaldo, Bizkaia, Spain
| | - Teresa C Delgado
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain.
| | - María Luz Martínez-Chantar
- Liver Disease Laboratory, Liver Metabolism Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain.
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Zhu Y, Guan Y, Loor JJ, Sha X, Coleman DN, Zhang C, Du X, Shi Z, Li X, Wang Z, Liu G, Li X. Fatty acid-induced endoplasmic reticulum stress promoted lipid accumulation in calf hepatocytes, and endoplasmic reticulum stress existed in the liver of severe fatty liver cows. J Dairy Sci 2019; 102:7359-7370. [PMID: 31155263 DOI: 10.3168/jds.2018-16015] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 04/04/2019] [Indexed: 01/22/2023]
Abstract
Disruption of endoplasmic reticulum (ER) homeostasis, often termed ER stress, is intrinsically linked with perturbation of lipid metabolism in humans and mice. Whether ER homeostasis is affected in cows experiencing fatty liver is unknown. The aim of this study was to investigate the potential role of ER stress in hepatic lipid accumulation in calf hepatocytes and ER stress status in dairy cows with severe fatty liver. In vitro experiments were conducted in which hepatocytes were isolated from calves and treated with different concentrations of fatty acids, tauroursodeoxycholic acid (TUDCA; a canonical inhibitor of ER stress), or both. The increase in phosphorylation level of protein kinase RNA-like ER kinase (PERK) and inositol requiring protein-1α (IRE1α) proteins, and the cleavage of activating transcription factor-6 (ATF6) protein in response to increasing doses of fatty acids (which were reversed by TUDCA treatment) in primary hepatocytes underscored a mechanistic link between fatty acids and ER stress. In addition, fatty acid treatment increased the abundance of sterol regulatory element-binding protein 1c, acetyl-CoA carboxylase-α, fatty acid synthase, and diacylglycerol acyltransferase 1, and lipid accumulation in calf primary hepatocytes, whereas inhibition of ER stress by incubating with TUDCA significantly weakened these effects. Overall, results in vitro indicate that inhibition of ER stress in calf hepatocytes alleviates fatty acid-induced lipid accumulation by downregulating the expression of lipogenic genes. In vivo experiments, liver and blood samples were collected from cows diagnosed as healthy (n = 15) or with severe fatty liver (n = 15). The phosphorylation level of PERK and IRE1α, the cleavage of ATF6 protein, and the abundance of several unfolded protein response genes (78 kDa glucose-regulated protein, AMP-dependent transcription factor 4, and spliced X-box binding protein 1) were greater in liver of cows with severe fatty liver. The present in vivo study confirms the occurrence of ER stress in dairy cows with severe fatty liver. Considering the causative role of fatty acid-induced ER stress in hepatic lipid accumulation in calf hepatocytes, the existence of ER stress in the liver of severe fatty liver cows may presage its participation in fatty liver progression in dairy cows. However, the mechanistic relationship between ER stress and fatty liver in dairy cows remain to be determined.
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Affiliation(s)
- Yiwei Zhu
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China
| | - Yuan Guan
- College of Animal Science, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China
| | - Juan J Loor
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801
| | - Xueying Sha
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China
| | - Danielle N Coleman
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801
| | - Cai Zhang
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471003, China
| | - Xiliang Du
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China
| | - Zhen Shi
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China
| | - Xiaobing Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China
| | - Zhe Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China
| | - Guowen Liu
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China
| | - Xinwei Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, Jilin, China.
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Zhang W, Xu J. Adaptive unfolded protein response promotes cell survival in rifampicin-treated L02 cells. Int J Mol Med 2018; 41:2233-2242. [PMID: 29393386 DOI: 10.3892/ijmm.2018.3438] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 01/23/2018] [Indexed: 11/05/2022] Open
Abstract
An important concept in drug-induced liver injury (DILI) is adaptation, which means the injury reverses with the continuation of the drug. The mechanism of adaption of drugs remains enigmatic, adaptive unfolded protein response (UPR) is possibly involved. We once observed adaptation phenomenon of rifampicin (RFP) in animal models, in this study, we investigate the effects of RFP on adaptive UPR in L02 cells, and after inhibiting UPR by using 4-phenylbutyrate (4-PBA), the change of cell viability and cell apoptosis in RFP-treated cells. We found that with the concentration of RFP increased and the treatment time was prolonged, the glucose-regulated protein 78 (GRP78), a hallmark of the UPR, was upregulated, and was dose- and time-dependent. RFP also activates the p-eukaryotic initiation factor 2α (eIF2α) protein expression. 4-PBA decreased GRP78 and p-eIF2α protein expression levels. Moreover, FCA showed that cell apoptosis rate obviously increased, and MTT assay showed that cell survival rate obviously decreased, this indicates that after inhibiting the UPR, the cell damage increased, which shows that the UPR is an adaptation mechanism to protect cells against injury induced by RFP. This also proves that when the degree of UPR induced by RFP is relatively mild, adaptive UPR is helpful for cell survival.
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Affiliation(s)
- Weiping Zhang
- Department of Gastroenterology, The First Affiliated Hospital of Anhui Medical University, Key Laboratory of Gastroenterology of Anhui Province, Hefei, Anhui 230022, P.R. China
| | - Jianming Xu
- Department of Gastroenterology, The First Affiliated Hospital of Anhui Medical University, Key Laboratory of Gastroenterology of Anhui Province, Hefei, Anhui 230022, P.R. China
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Anavi S, Madar Z, Tirosh O. Non-alcoholic fatty liver disease, to struggle with the strangle: Oxygen availability in fatty livers. Redox Biol 2017; 13:386-392. [PMID: 28667907 PMCID: PMC5493836 DOI: 10.1016/j.redox.2017.06.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 06/18/2017] [Accepted: 06/20/2017] [Indexed: 12/29/2022] Open
Abstract
Nonalcoholic fatty liver diseases (NAFLD) is one of the most common chronic liver disease in Western countries. Oxygen is a central component of the cellular microenvironment, which participate in the regulation of cell survival, differentiation, functions and energy metabolism. Accordingly, sufficient oxygen supply is an important factor for tissue durability, mainly in highly metabolic tissues, such as the liver. Accumulating evidence from the past few decades provides strong support for the existence of interruptions in oxygen availability in fatty livers. This outcome may be the consequence of both, impaired systemic microcirculation and cellular membrane modifications which occur under steatotic conditions. This review summarizes current knowledge regarding the main factors which can affect oxygen supply in fatty liver.
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Affiliation(s)
- Sarit Anavi
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Israel; Peres Academic Center, Rehovot, Israel
| | - Zecharia Madar
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Israel
| | - Oren Tirosh
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Israel.
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Lee SE, Takagi Y, Nishizaka T, Baek JH, Kim HJ, Lee SH. Subclinical cutaneous inflammation remained after permeability barrier disruption enhances UV sensitivity by altering ER stress responses and topical pseudoceramide prevents them. Arch Dermatol Res 2017; 309:541-50. [PMID: 28631090 DOI: 10.1007/s00403-017-1753-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Stratum corneum forms the UV barrier. The effect of ultraviolet B (UVB) on normal skin was extensively studied; however, its effect on barrier perturbed skin remains undefined. Both barrier perturbation and UVB irradiation induce endoplasmic reticulum (ER) stress and unfolded protein response (UPR) in keratinocytes. Mild ER stress activates homeostatic UPR, while severe ER stress leads to abnormal UPR, promoting apoptosis and inflammation. Here, we investigated UV sensitivity and UVB-induced UPR in barrier-disrupted human skin and the effects of pseudoceramide-dominant emollient on UVB-induced skin responses. Tape-stripped skin of healthy volunteers showed enhanced susceptibility to erythema and augmented proinflammatory cytokines induction following suberythemal UVB irradiation. Suberythemal UVB activated XBP1 in normal skin, while increased CHOP transcription in barrier perturbed skin. After tape stripping, pseudoceramide-dominant emollient was applied for 3 days, and then, the areas were irradiated with suberythemal UVB. Pretreatment with topical pseudoceramide protected against UVB-induced upregulation of IL-1β, IL-6, and TNF-α transcription and reduced susceptibility to erythema following UVB. Topical pseudoceramide also suppressed suberythemal UVB-induced CHOP transcription in barrier-disrupted skin. Taken together, these data indicate that permeability barrier disruption increases UV sensitivity in human skin, partly via switch the UVB-induced UPR, from homeostatic signals to pro-apoptotic and proinflammatory signals. In addition, we conclude that pseudoceramide-dominant emollient suppresses excessive ER stress induction and CHOP activation following UVB in barrier damaged skin, providing evidence that pseudoceramide-dominant emollients can be promising strategies for photoprotection of the barrier damaged skin.
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Dai F, Jiang T, Bao YY, Chen GJ, Chen L, Zhang Q, Lu YX. Fenofibrate improves high-fat diet-induced and palmitate-induced endoplasmic reticulum stress and inflammation in skeletal muscle. Life Sci. 2016;157:158-167. [PMID: 27297630 DOI: 10.1016/j.lfs.2016.06.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/31/2016] [Accepted: 06/07/2016] [Indexed: 02/07/2023]
Abstract
AIMS Fenofibrate (FF) is commonly used clinically as a lipid-lowering drug, but whether it participates in endoplasmic reticulum (ER) stress and decreases inflammation in skeletal muscle is still unknown. The aim of this study is to determine whether FF treatment reduces insulin resistance (IR) by alleviating ER stress and downstream inflammation in skeletal muscle tissues and cells. MAIN METHODS Female SD rats were randomly divided into groups receiving the standard chow diet (SCD), a high-fat diet (HFD), or HFD plus FF (HFD+FF). The rats in the latter two groups were subjected to a standard HFD for 20weeks, then the HFD+FF rats were administered FF (30mg/kg once daily via gavage) for another 8weeks. Whole-body IR, expression of peroxisome proliferator-activated receptor α (PPARα), ER stress-related genes, and inflammatory genes in the soleus muscle were assessed. The differentiated C2C12 myotubes were treated with palmitic acid or pretreated with fenofibric acid or 4-phenylbutyric acid (4-PBA), etomoxir, and the expression of ER stress, beta-oxidation-related genes, inflammatory genes, Toll-like receptor 4 (TLR4), and insulin-signaling-related molecules were determined. KEY FINDINGS Eight weeks of FF treatment attenuated HFD-induced IR by decreased tribbles 3 (TRB3) expression, ER stress and inflammation in skeletal muscle. FA pretreatment markedly inverted the PA-induced expression of TLR4 and downstream inflammatory genes, activated ER stress, improved β-oxidation and insulin signaling in differentiated myotube cells. SIGNIFICANCE FF treatment significantly improved HFD-induced IR in skeletal muscle and PA-induced IR in myotube cells, which may be related to reduced ER stress-induced inflammation.
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Jung TW, Choi KM. Pharmacological Modulators of Endoplasmic Reticulum Stress in Metabolic Diseases. Int J Mol Sci 2016; 17:ijms17020192. [PMID: 26840310 PMCID: PMC4783926 DOI: 10.3390/ijms17020192] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 01/20/2016] [Accepted: 01/27/2016] [Indexed: 01/23/2023] Open
Abstract
The endoplasmic reticulum (ER) is the principal organelle responsible for correct protein folding, a step in protein synthesis that is critical for the functional conformation of proteins. ER stress is a primary feature of secretory cells and is involved in the pathogenesis of numerous human diseases, such as certain neurodegenerative and cardiometabolic disorders. The unfolded protein response (UPR) is a defense mechanism to attenuate ER stress and maintain the homeostasis of the organism. Two major degradation systems, including the proteasome and autophagy, are involved in this defense system. If ER stress overwhelms the capacity of the cell's defense mechanisms, apoptotic death may result. This review is focused on the various pharmacological modulators that can protect cells from damage induced by ER stress. The possible mechanisms for cytoprotection are also discussed.
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Affiliation(s)
- Tae Woo Jung
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Korea University, Seoul 152-703, Korea.
| | - Kyung Mook Choi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Korea University, Seoul 152-703, Korea.
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Zhang N, Lu Y, Shen X, Bao Y, Cheng J, Chen L, Li B, Zhang Q. Fenofibrate treatment attenuated chronic endoplasmic reticulum stress in the liver of nonalcoholic fatty liver disease mice. Pharmacology 2015; 95:173-80. [PMID: 25896720 DOI: 10.1159/000380952] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/13/2015] [Indexed: 12/31/2022]
Abstract
Fenofibrate is widely used in clinical practice, but its influence on chronic endoplasmic reticulum (ER) stress induced by feeding a high-calorie and high-cholesterol diet (HCD) has still not been studied. We thus investigated its effects on the liver of the nonalcoholic fatty liver disease (NAFLD) mouse model. Male C57BL/6 mice fed an HCD for 3 months were treated with fenofibrate (HCD + FF, 40 mg/kg, once daily) via gavage for 4 weeks. Insulin sensitivity, serum lipid and inflammatory cytokines were measured. Liver tissues were procured for histological examination as well as analysis of hepatic triglyceride levels, distribution of inflammatory cytokines and genes involved in ER stress. Our results showed that chronic feeding of an HCD successfully induced an NAFLD model accompanied by inflammatory activation, apoptosis and severe ER stress in the liver. Fenofibrate administration significantly improved symptoms of NAFLD and decreased apoptosis, expression of inflammatory cytokines and genes involved in ER stress, such as inositol-requiring enzyme 1α (IRE1α), X-box binding protein 1 (XBP1) and JNK phosphorylation. Thus, our study suggests that fenofibrate protected against inflammatory injury and apoptosis, maybe alleviating ER stress through the IRE1α-XBP1-JNK pathway in the liver of NAFLD mice.
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Affiliation(s)
- Nan Zhang
- Department of Endocrinology, First Affiliated Hospital of Anhui Medical University, Hefei, China
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Lu Y, Cheng J, Chen L, Li C, Chen G, Gui L, Shen B, Zhang Q. Endoplasmic reticulum stress involved in high-fat diet and palmitic acid-induced vascular damages and fenofibrate intervention. Biochem Biophys Res Commun 2015; 458:1-7. [DOI: 10.1016/j.bbrc.2014.12.123] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 12/18/2014] [Indexed: 12/25/2022]
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13
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Seeßle J, Liebisch G, Schmitz G, Stremmel W, Chamulitrat W. Palmitate activation by fatty acid transport protein 4 as a model system for hepatocellular apoptosis and steatosis. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:549-65. [PMID: 25603556 DOI: 10.1016/j.bbalip.2015.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/18/2014] [Accepted: 01/09/2015] [Indexed: 12/15/2022]
Abstract
Fatty acid transport protein (FATP) 4 is a minor FATP in the liver but it has some activity towards palmitate 16:0 (Pal). We here chose FATP4 as a representative model enzyme for acyl-CoA synthetases (ACSs), and FATPs to determine whether Pal activation would lead to apoptosis and alteration in lipid metabolism. By using FATP4 overexpressed (FATP4) Huh-7 cells, we showed that FATP4 was localized in the endoplasmic reticulum (ER) and mitochondria of FATP4 cells. FATP4 cells were more responsive to Pal than the control GFP cells in increasing palmitoyl-CoA and oleoyl-CoA activities as well as apoptosis by ~2-3 folds. The lipoapoptosis susceptibility by FATP4 was coupled with the increased JNK, PUMA, caspase3, PARP-1 activation as well as Rac-1-mediated cytoskeletal reorganization, and decreased insulin sensitivity. This was associated with increased contents of neutral lipids and significant alteration in composition of phospholipids and sphingolipids including increased lysophosphatidylcholine (LPC), ceramide, and hexosylceramide, as well as an increase of saturated:polyunsaturated fatty acid ratio in LPC and PC, but a decrease of this ratio in phosphatidylethanolamine pool. By use of ceramide synthase inhibitors, our results showed that FATP4-sensitized lipoapoptosis was not mediated by ceramides. Moreover, FATP4 expression was increased in fatty livers in vivo. Thus, our model system has provided a clue that Pal activation FATP4 triggers hepatocellular apoptosis via altered phospholipid composition and steatosis by acylation into complex lipids. This may be a redundant mechanism for other ER-localizing ACSs and FATPs in the liver, and hence their involvement in the development of fatty liver disease.
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Affiliation(s)
- Jessica Seeßle
- Department of Internal Medicine IV, Gastroenterology and Infectious Disease, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Gerhard Liebisch
- Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Gerd Schmitz
- Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Wolfgang Stremmel
- Department of Internal Medicine IV, Gastroenterology and Infectious Disease, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Walee Chamulitrat
- Department of Internal Medicine IV, Gastroenterology and Infectious Disease, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany.
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Abstract
Hepatitis C virus (HCV) is a single-stranded, positive-sense RNA virus of clinical importance. The virus establishes a chronic infection and can progress from chronic hepatitis, steatosis to fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). The mechanisms of viral persistence and pathogenesis are poorly understood. Recently the unfolded protein response (UPR), a cellular homeostatic response to endoplasmic reticulum (ER) stress, has emerged to be a major contributing factor in many human diseases. It is also evident that viruses interact with the host UPR in many different ways and the outcome could be pro-viral, anti-viral or pathogenic, depending on the particular type of infection. Here we present evidence for the elicitation of chronic ER stress in HCV infection. We analyze the UPR signaling pathways involved in HCV infection, the various levels of UPR regulation by different viral proteins and finally, we propose several mechanisms by which the virus provokes the UPR.
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Affiliation(s)
- Shiu-Wan Chan
- Faculty of Life Sciences, The University of Manchester Manchester, UK
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Wang HW, Cao LL, Fan MQ. Effect of polyene phosphatidylcholine combined with fenofibrate capsules in treatment of nonalcoholic steatohepatitis. Shijie Huaren Xiaohua Zazhi 2014; 22:429-433. [DOI: 10.11569/wcjd.v22.i3.429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the efficacy and safety of polyene phosphatidylcholine combined with fenofibrate capsules in the treatment of nonalcoholic steatohepatitis (NASH).
METHODS: A total of 124 patients with NASH were selected and divided randomly into two groups: a treatment group and two control groups. The treatment group received polyene phosphatidylcholine combined with fenofibrate capsules (n = 45) for 12 wk, while the two control groups received fenofibrate capsules and inosine (n = 43) and polyene phosphatidylcholine alone (n = 36) for the same duration, respectively. The levels of serum transaminase, clinical symptoms, blood lipids and B-mode ultrasonic imaging findings before and after treatment were compared between groups.
RESULTS: The levels of serum transaminase, clinical symptoms, blood lipids and B-mode ultrasonic imaging findings improved obviously after treatment. The response rates were 86.7%, 53.5% and 88.9% in the treatment group and the two control groups, respectively. There were significant differences between the three groups in the improvement of clinical symptoms, liver function and blood lipids (P < 0.05 for all).
CONCLUSION: Treatment of NASH with fenofibrate capsules combined with polyene phosphatidylcholine is safe and effective.
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Hu N, Hu M, Duan R, Liu C, Guo H, Zhang M, Yu Y, Wang X, Liu L, Liu X. Increased Levels of Fatty Acids Contributed to Induction of Hepatic CYP3A4 Activity Induced by Diabetes — In Vitro Evidence From HepG2 Cell and Fa2N-4 Cell Lines. J Pharmacol Sci 2014; 124:433-44. [DOI: 10.1254/jphs.13212fp] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Hsu YJ, Wang LC, Yang WS, Yang CM, Yang CH. Effects of fenofibrate on adiponectin expression in retinas of streptozotocin-induced diabetic rats. J Diabetes Res 2014; 2014:540326. [PMID: 25525608 PMCID: PMC4267464 DOI: 10.1155/2014/540326] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 11/10/2014] [Accepted: 11/10/2014] [Indexed: 12/16/2022] Open
Abstract
Adiponectin has been associated with increased risks of microvascular complications in diabetes; however, its role in the development of diabetic retinopathy (DR) is unknown. Fenofibrate is a lipid-lowering agent that has been shown to be capable of preventing DR progression. We investigated the expression of adiponectin and its receptors in DR and evaluated the effects of fenofibrate on their expression. The mRNA and protein levels of adiponectin and its receptors were elevated in retinas of streptozotocin-induced diabetic rats and were suppressed following fenofibrate treatment. Immunofluorescence staining demonstrated that adiponectin and adipoR1 were expressed in cells located within blood vessels, the retinal ganglion, and the inner nuclear layer. AdipoR1 was strongly expressed whereas adipoR2 was only weekly expressed in vascular endothelial cells. The in vitro experiments showed that adiponectin expression was induced by high glucose concentrations in RGC-5 and RAW264.7 cells and was suppressed following fenofibrate treatment. AdipoR1 and adipoR2 levels in RGC-5 cells were elevated in high glucose concentrations and suppressed by fenofibrate. Our results demonstrated that adiponectin may be a proinflammatory mediator in diabetic retinas and fenofibrate appears to modulate the expression of adiponectin and its receptors in diabetic retinas, effectively reducing DR progression.
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Affiliation(s)
- Ying-Jung Hsu
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Lu-Chun Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan
| | - Wei-Shiung Yang
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei 100, Taiwan
| | - Chung-May Yang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan
| | - Chang-Hao Yang
- Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, No. 7 Chung-Shan South Road, Taipei 100, Taiwan
- *Chang-Hao Yang:
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Kostapanos MS, Kei A, Elisaf MS. Current role of fenofibrate in the prevention and management of non-alcoholic fatty liver disease. World J Hepatol 2013; 5:470-478. [PMID: 24073298 PMCID: PMC3782684 DOI: 10.4254/wjh.v5.i9.470] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Revised: 07/24/2013] [Accepted: 08/20/2013] [Indexed: 02/06/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a common health problem with a high mortality burden due to its liver- and vascular-specific complications. It is associated with obesity, high-fat diet as well as with type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS). Impaired hepatic fatty acid (FA) turnover together with insulin resistance are key players in NAFLD pathogenesis. Peroxisome proliferator-activated receptors (PPARs) are involved in lipid and glucose metabolic pathways. The novel concept is that the activation of the PPARα subunit may protect from liver steatosis. Fenofibrate, by activating PPARα, effectively improves the atherogenic lipid profile associated with T2DM and MetS. Experimental evidence suggested various protective effects of the drug against liver steatosis. Namely, fenofibrate-related PPARα activation may enhance the expression of genes promoting hepatic FA β-oxidation. Furthermore, fenofibrate reduces hepatic insulin resistance. It also inhibits the expression of inflammatory mediators involved in non-alcoholic steatohepatitis pathogenesis. These include tumor necrosis factor-α, intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1. Consequently, fenofibrate can limit hepatic macrophage infiltration. Other liver-protective effects include decreased oxidative stress and improved liver microvasculature function. Experimental studies showed that fenofibrate can limit liver steatosis associated with high-fat diet, T2DM and obesity-related insulin resistance. Few studies showed that these benefits are also relevant even in the clinical setting. However, these have certain limitations. Namely, these were uncontrolled, their sample size was small, fenofibrate was used as a part of multifactorial approach, while histological data were absent. In this context, there is a need for large prospective studies, including proper control groups and full assessment of liver histology.
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Chamulitrat W, Liebisch G, Xu W, Gan-Schreier H, Pathil A, Schmitz G, Stremmel W. Ursodeoxycholyl lysophosphatidylethanolamide inhibits lipoapoptosis by shifting fatty acid pools toward monosaturated and polyunsaturated fatty acids in mouse hepatocytes. Mol Pharmacol 2013; 84:696-709. [PMID: 23974795 DOI: 10.1124/mol.113.088039] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE) is a hepatoprotectant in inhibiting apoptosis, inflammation, and hyperlipidemia in mouse models of nonalcoholic steatohepatitis (NASH). We studied the ability of UDCA-LPE to inhibit palmitate (Pal)-induced apoptosis in primary hepatocytes and delineate cytoprotective mechanisms. We showed that lipoprotection by UDCA-LPE was mediated by cAMP and was associated with increases in triglycerides (TGs) and phospholipids (PLs). An inhibitor of cAMP-effector protein kinase A partially reversed the protective effects of UDCA-LPE. Lipidomic analyses of fatty acids and PL composition revealed a shift of lipid metabolism from saturated Pal to monounsaturated and polyunsaturated fatty acids, mainly, oleate, docosapentaenoate, and docosahexaenoate. The latter two ω-3 fatty acids were particularly found in phosphatidylcholine and phosphatidylserine pools. The catalysis of Pal by stearoyl-CoA desaturase-1 (SCD-1) is a known mechanism for the channeling of Pal away from apoptosis. SCD-1 protein was upregulated during UDCA-LPE lipoprotection. SCD-1 knockdown of Pal-treated cells showed further increased apoptosis, and the extent of UDCA-LPE protection was reduced. Thus, the major mechanism of UDCA-LPE lipoprotection involved a metabolic shift from toxic saturated toward cytoprotective unsaturated fatty acids in part via SCD-1. UDCA-LPE may thus be a therapeutic agent for treatment of NASH by altering distinct pools of fatty acids for storage into TGs and PLs, and the latter may protect lipotoxicity at the membrane levels.
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Affiliation(s)
- Walee Chamulitrat
- Department of Internal Medicine IV, Gastroenterology and Infectious Diseases, Im Neuenheimer Feld, Heidelberg, Germany (W.C., H.G.-S., A.P., W.S.); Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Regensburg, Germany (G.L., G.S.); and Department of Gastroenterology, Hangzhou First People's Hospital, Hangzhou, Zhejiang, People's Republic of China (W.X.)
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Hiyama Y, Marshall AH, Kraft R, Arno A, Jeschke MG. Fenofibrate does not affect burn-induced hepatic endoplasmic reticulum stress. J Surg Res 2013; 185:733-9. [PMID: 23866789 DOI: 10.1016/j.jss.2013.06.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 05/23/2013] [Accepted: 06/13/2013] [Indexed: 11/21/2022]
Abstract
BACKGROUND Burn injury causes major metabolic derangements such as hypermetabolism, hyperlipidemia, and insulin resistance and is associated with liver damage, hepatomegaly, and hepatic endoplasmic reticulum (ER) stress. Although the physiological consequences of such derangements have been delineated, the underlying molecular mechanisms remain unknown. Previously, it was shown that fenofibrate improves patient outcome by attenuating postburn stress responses. METHODS Fenofibrate, a peroxisome proliferator-activated receptor alpha agonist, regulates liver lipid metabolism and has been used to treat hypertriglyceridemia and hypercholesterolemia for many years. The aim of the present study is to determine the effects of fenofibrate on burn-induced hepatic morphologic and metabolic changes. We randomized rats to sham, burn injury, and burn injury plus fenofibrate. Animals were sacrificed and livers were assessed at 24 or 48 h post burn. RESULTS Burn injury decreased albumin and increased alanine transaminase (P = 0.1 versus sham), indicating liver injury. Fenofibrate administration did not restore albumin or decrease alanine transaminase. In addition, ER stress was significantly increased after burn injury both with and without fenofibrate (P < 0.05 versus sham). Burn injury increased fatty acid metabolism gene expression (P < 0.05 versus sham), downstream of peroxisome proliferator-activated receptor alpha. Fenofibrate treatment increased fatty acid metabolism further, which reduced postburn hepatic steatosis (burn versus sham P < 0.05, burn + fenofibrate versus sham not significant). CONCLUSIONS Fenofibrate did not alleviate thermal injury-induced hepatic ER stress and dysfunction, but it reduced hepatic steatosis by modulating hepatic genes related to fat metabolism.
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Jeong YT, Kim YD, Jung YM, Park DC, Lee DS, Ku SK, Li X, Lu Y, Chao GH, Kim KJ, Lee JY, Baek MC, Kang W, Hwang SL, Chang HW. Low Molecular Weight Fucoidan Improves Endoplasmic Reticulum Stress-Reduced Insulin Sensitivity through AMP-Activated Protein Kinase Activation in L6 Myotubes and Restores Lipid Homeostasis in a Mouse Model of Type 2 Diabetes. Mol Pharmacol 2013; 84:147-57. [DOI: 10.1124/mol.113.085100] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Hwang SL, Yang JH, Jeong YT, Kim YD, Li X, Lu Y, Chang YC, Son KH, Chang HW. Tanshinone IIA improves endoplasmic reticulum stress-induced insulin resistance through AMP-activated protein kinase. Biochem Biophys Res Commun 2013; 430:1246-52. [DOI: 10.1016/j.bbrc.2012.12.066] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 12/17/2012] [Indexed: 12/11/2022]
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Qadri I, Choudhury M, Rahman SM, Knotts TA, Janssen RC, Schaack J, Iwahashi M, Puljak L, Simon FR, Kilic G, Fitz JG, Friedman JE. Increased phosphoenolpyruvate carboxykinase gene expression and steatosis during hepatitis C virus subgenome replication: role of nonstructural component 5A and CCAAT/enhancer-binding protein β. J Biol Chem 2012; 287:37340-51. [PMID: 22955269 DOI: 10.1074/jbc.m112.384743] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chronic hepatitis C virus (HCV) infection greatly increases the risk for type 2 diabetes and nonalcoholic steatohepatitis; however, the pathogenic mechanisms remain incompletely understood. Here we report gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) transcription and associated transcription factors are dramatically up-regulated in Huh.8 cells, which stably express an HCV subgenome replicon. HCV increased activation of cAMP response element-binding protein (CREB), CCAAT/enhancer-binding protein (C/EBPβ), forkhead box protein O1 (FOXO1), and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and involved activation of the cAMP response element in the PEPCK promoter. Infection with dominant-negative CREB or C/EBPβ-shRNA significantly reduced or normalized PEPCK expression, with no change in PGC-1α or FOXO1 levels. Notably, expression of HCV nonstructural component NS5A in Huh7 or primary hepatocytes stimulated PEPCK gene expression and glucose output in HepG2 cells, whereas a deletion in NS5A reduced PEPCK expression and lowered cellular lipids but was without effect on insulin resistance, as demonstrated by the inability of insulin to stimulate mobilization of a pool of insulin-responsive vesicles to the plasma membrane. HCV-replicating cells demonstrated increases in cellular lipids with insulin resistance at the level of the insulin receptor, increased insulin receptor substrate 1 (Ser-312), and decreased Akt (Ser-473) activation in response to insulin. C/EBPβ-RNAi normalized lipogenic genes sterol regulatory element-binding protein-1c, peroxisome proliferator-activated receptor γ, and liver X receptor α but was unable to reduce accumulation of triglycerides in Huh.8 cells or reverse the increase in ApoB expression, suggesting a role for increased lipid retention in steatotic hepatocytes. Collectively, these data reveal an important role of NS5A, C/EBPβ, and pCREB in promoting HCV-induced gluconeogenic gene expression and suggest that increased C/EBPβ and NS5A may be essential components leading to increased gluconeogenesis associated with HCV infection.
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Affiliation(s)
- Ishtiaq Qadri
- Department of Pediatrics, University of Colorado Denver, Aurora, Colorado 80045, USA
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Rahman SM, Janssen RC, Choudhury M, Baquero KC, Aikens RM, de la Houssaye BA, Friedman JE. CCAAT/enhancer-binding protein β (C/EBPβ) expression regulates dietary-induced inflammation in macrophages and adipose tissue in mice. J Biol Chem 2012; 287:34349-60. [PMID: 22902781 DOI: 10.1074/jbc.m112.410613] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Strong evidence exists for a link between chronic low level inflammation and dietary-induced insulin resistance; however, little is known about the transcriptional networks involved. Here we show that high fat diet (HFD) or saturated fatty acid exposure directly activates CCAAT/enhancer-binding protein β (C/EBPβ) protein expression in liver, adipocytes, and macrophages. Global C/EBPβ deletion prevented HFD-induced inflammation and surprisingly increased mitochondrial gene expression in white adipose tissue along with brown adipose tissue markers PRDM16, CIDEa, and UCP1, consistent with a resistance to HFD-induced obesity. In isolated peritoneal macrophages from C/EBPβ(-/-) mice, the anti-inflammatory gene LXRα and its targets SCD1 and DGAT2 were strikingly up-regulated along with IL-10, while NLRP3, a gene important for activating the inflammasome, was suppressed in response to palmitate. Using RAW 264.7 macrophage cells or 3T3-L1 adipocytes, C/EBPβ knockdown prevented palmitate-induced inflammation and p65-NFκB DNA binding activity, while C/EBPβ overexpression induced NFκB binding, JNK activation, and pro-inflammatory cytokine gene expression directly. Finally, chimeric bone marrow mice transplanted with bone marrow lacking C/EBPβ(-/-) demonstrated reduced systemic and adipose tissue inflammatory markers, macrophage content, and maintained insulin sensitivity on HFD. Taken together, these results demonstrate that HFD or palmitate exposure triggers C/EBPβ expression that controls expression of distinct aspects of alternative macrophage activation. Reducing C/EBPβ in macrophages confers protection from HFD-induced systemic inflammation and insulin resistance, suggesting it may be an attractive therapeutic target for ameliorating obesity-induced inflammatory responses.
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Affiliation(s)
- Shaikh M Rahman
- Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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Basseri S, Austin RC. Endoplasmic reticulum stress and lipid metabolism: mechanisms and therapeutic potential. Biochem Res Int 2012; 2012:841362. [PMID: 22195283 DOI: 10.1155/2012/841362] [Citation(s) in RCA: 148] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 10/18/2011] [Indexed: 12/11/2022] Open
Abstract
The endoplasmic reticulum (ER) plays a crucial role in protein folding, assembly, and secretion. Disruption of ER homeostasis may lead to accumulation of misfolded or unfolded proteins in the ER lumen, a condition referred to as ER stress. In response to ER stress, a signal transduction pathway known as the unfolded protein response (UPR) is activated. UPR activation allows the cell to cope with an increased protein-folding demand on the ER. Recent studies have shown that ER stress/UPR activation plays a critical role in lipid metabolism and homeostasis. ER-stress-dependent dysregulation of lipid metabolism may lead to dyslipidemia, insulin resistance, cardiovascular disease, type 2 diabetes, and obesity. In this paper, we examine recent findings illustrating the important role ER stress/UPR signalling pathways play in regulation of lipid metabolism, and how they may lead to dysregulation of lipid homeostasis.
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Bassendine MF, Sheridan DA, Felmlee DJ, Bridge SH, Toms GL, Neely RDG. HCV and the hepatic lipid pathway as a potential treatment target. J Hepatol 2011; 55:1428-40. [PMID: 21718665 DOI: 10.1016/j.jhep.2011.06.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 06/15/2011] [Accepted: 06/17/2011] [Indexed: 02/07/2023]
Abstract
Atherosclerosis has been described as a liver disease of the heart [1]. The liver is the central regulatory organ of lipid pathways but since dyslipidaemias are major contributors to cardiovascular disease and type 2 diabetes rather than liver disease, research in this area has not been a major focus for hepatologists. Virus-host interaction is a continuous co-evolutionary process [2] involving the host immune system and viral escape mechanisms [3]. One of the strategies HCV has adopted to escape immune clearance and establish persistent infection is to make use of hepatic lipid pathways. This review aims to: • update the hepatologist on lipid metabolism • review the evidence that HCV exploits hepatic lipid pathways to its advantage • discuss approaches to targeting host lipid pathways as adjunctive therapy.
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Frederico MJ, Vitto MF, Cesconetto PA, Engelmann J, De Souza DR, Luz G, Pinho RA, Ropelle ER, Cintra DE, De Souza CT. Short-term inhibition of SREBP-1c expression reverses diet-induced non-alcoholic fatty liver disease in mice. Scand J Gastroenterol 2011; 46:1381-8. [PMID: 21936721 DOI: 10.3109/00365521.2011.613945] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE The present study investigates the level of Sterol-regulatory element-binding proteins (SREBP-1c) and related proteins in obese mice (DIO) treated with SREBP-1c antisense oligonucleotide (ASO) to observe a reversal of steatosis. MATERIALS AND METHODS Swiss mice were fed on chow containing 61 kJ% saturated fat for 8 weeks to develop obesity. After this period, one group of animals was used to assess the molecular effects of SREBP-1c antisense oligonucleotide treatment by immunoblot analysis in a dose-response curve (0; 1.0; 2.0; 3.0; 4.0 nmol/day). After the dose (3.0 nmol/day) was determined, another group was treated for 14 days. After a period of 24 h following the last injection mice were killed and plasma and hepatic tissue were obtained to evaluate plasma triglycerides and total liver fat. Western blot was performed to evaluate SREBP-1c, FAS, SCD-1, PPARγ and CPT1 expression and AMPK[Thr172] and ACC[Ser79] phosphorylation. Livers were stained using the hematoxylin and eosin method for histological analysis. RESULTS Body weight, epididymal fat and glucose levels were not affected by one daily dose of ASO. However, total plasma triglycerides and total liver fat were significantly reduced. Also, this treatment inhibited SREBP-1c and reduced protein levels of a series of proteins involved in lipogenesis, including ACC, FAS and SCD-1. Moreover, mice treated with ASO presented a significant reduction in macroscopic and microscopic features of hepatic steatosis. CONCLUSION Our results demonstrate that the inhibition of SREBP-1c decreased the expression of lipogenic enzymes, reducing the accumulation of triglycerides and, finally, reversing hepatic steatosis in mice.
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Affiliation(s)
- Marisa Js Frederico
- Laboratory of Exercise Biochemistry and Physiology, Health Sciences Unit, University of Southern Santa Catarina, Criciúma, SC, Brazil
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Liang X, Hu M, Rogers CQ, Shen Z, You M. Role of SIRT1-FoxO1 signaling in dietary saturated fat-dependent upregulation of liver adiponectin receptor 2 in ethanol-administered mice. Antioxid Redox Signal 2011; 15:425-35. [PMID: 21194380 PMCID: PMC3118604 DOI: 10.1089/ars.2010.3780] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The aim of the present study is to examine the effects of dietary saturated fatty acids on liver adiponectin receptor 1 (AdipoR1) and adiponectin receptor 2 (AdipoR2) in ethanol-administered animals and in ethanol-exposed cultured hepatic cells, and to explore the underlying molecular mechanisms. The mRNA and protein levels of hepatic AdipoR2 were selectively increased by chronic ethanol feeding to mice consuming a diet high in saturated fat (HSF). Administration of an HSF diet blocked hyperacetylation of forkhead transcription factor 1 (FoxO1), a known target of sirtuin 1 (SIRT1), increased nuclear FoxO1 protein levels, and enhanced association of FoxO1 with the AdipoR2 promoter in the livers of ethanol-fed mice. Treatment of cultured hepatic cells with palmitic acid (a major saturated fatty acid in HSF diet) in the presence of ethanol robustly increased AdipoR2 mRNA expression and enhanced activity of a mouse AdipoR2 promoter. Knocking down SIRT1 or FoxO1 using the small silencing SIRT1 or FoxO1 plasmid blunted the palmitic acid effect. Taken together, these results reveal that dietary saturated fat selectively upregulates hepatic AdipoR2 through modulation of SIRT1-FoxO1 signaling in ethanol fed mice, and this effect may contribute to the protective effect of the HSF diet against alcoholic fatty liver.
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Affiliation(s)
- Xiaomei Liang
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida 33612, USA
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Buechler C, Wanninger J, Neumeier M. Adiponectin, a key adipokine in obesity related liver diseases. World J Gastroenterol 2011; 17:2801-11. [PMID: 21734787 PMCID: PMC3120939 DOI: 10.3748/wjg.v17.i23.2801] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 11/17/2010] [Accepted: 11/24/2010] [Indexed: 02/06/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) comprising hepatic steatosis, non-alcoholic steatohepatitis (NASH), and progressive liver fibrosis is considered the most common liver disease in western countries. Fatty liver is more prevalent in overweight than normal-weight people and liver fat positively correlates with hepatic insulin resistance. Hepatic steatosis is regarded as a benign stage of NAFLD but may progress to NASH in a subgroup of patients. Besides liver biopsy no diagnostic tools to identify patients with NASH are available, and no effective treatment has been established. Visceral obesity is a main risk factor for NAFLD and inappropriate storage of triglycerides in adipocytes and higher concentrations of free fatty acids may add to increased hepatic lipid storage, insulin resistance, and progressive liver damage. Most of the adipose tissue-derived proteins are elevated in obesity and may contribute to systemic inflammation and liver damage. Adiponectin is highly abundant in human serum but its levels are reduced in obesity and are even lower in patients with hepatic steatosis or NASH. Adiponectin antagonizes excess lipid storage in the liver and protects from inflammation and fibrosis. This review aims to give a short survey on NAFLD and the hepatoprotective effects of adiponectin.
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Abstract
INTRODUCTION Hepatic steatosis is the histological observation of numerous lipid inclusions due to an excess accumulation of triacylglycerols. They are a concern with new therapeutic candidates because they signify altered lipid metabolism that can progress to more serious liver toxicity. AREAS COVERED This article is based on an article search using the PubMed database from 1987 to 2011 and confirms associations for several previously marketed drugs with four basic hepatocellular mechanisms. The article also describes how these mechanisms are controlled by master regulators of lipid metabolism, which include gene transcription factors, nuclear receptors, hormonal signaling, energy sensing proteins, endoplasmic reticulum stress signaling and certain key metabolic intermediates. EXPERT OPINION Drug-induced hepatic steatosis is typically not detectable by conventional means other than invasive histological examinations. By understanding the basic mechanisms, key regulators and energy signaling systems of the liver, the investigator is better equipped to avoid xenobiotics with steatogenic potential in the drug discovery or early development process. There are now a number of methods for detecting this potential, specifically gene expression or metabolomic profiling and pathway analysis or mechanism-based in vitro systems.
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Wang XB, Huang XM, Ochs T, Li XY, Jin HF, Tang CS, Du JB. Effect of sulfur dioxide preconditioning on rat myocardial ischemia/reperfusion injury by inducing endoplasmic reticulum stress. Basic Res Cardiol 2011; 106:865-78. [DOI: 10.1007/s00395-011-0176-x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 03/04/2011] [Accepted: 03/26/2011] [Indexed: 01/18/2023]
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Choudhury M, Qadri I, Rahman SM, Schroeder-Gloeckler J, Janssen RC, Friedman JE. C/EBPβ is AMP kinase sensitive and up-regulates PEPCK in response to ER stress in hepatoma cells. Mol Cell Endocrinol 2011; 331:102-8. [PMID: 20797423 PMCID: PMC2981635 DOI: 10.1016/j.mce.2010.08.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 08/12/2010] [Accepted: 08/17/2010] [Indexed: 01/11/2023]
Abstract
Diabetes and obesity are associated with activation of endoplasmic reticulum (ER) stress; however a direct link between ER stress and increased hepatic gluconeogenesis remains unclear. Here we show that ER stress triggers a significant increase in expression of CCAAT/enhancer-binding protein (C/EBPβ) and phosphorylated CREB together with reduced phospho-AMP-activated protein kinase (pAMPK) in hepatoma cells. ER stress contributed to transcriptional activation of the gluconeogenic phosphoenolpyruvate carboxykinase (PEPCK) promoter in Huh7 and HepG2 cells via cAMP binding motif (CRE site). Chromatin immunoprecipitation assays demonstrate that C/EBPβ is recruited to the PEPCK promoter during ER stress and is reversed by pre-treatment with a JNK inhibitor that relieves ER stress. C/EBPβ but not pCREB was suppressed by the AMPK-activator AICAR or constitutively active AMPK, while dominant negative AMPK increased C/EBPβ expression. These data suggest that ER stress triggers suppression of AMPK while increasing C/EBPβ and pCREB expression which activates PEPCK gene transcription. Understanding how ER stress suppresses AMPK activation and increases C/EBPβ expression could lead to a potentially novel pathway for treatment of diabetes.
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Affiliation(s)
- Mahua Choudhury
- Department of Pediatrics, University of Colorado Denver, Aurora, CO 80045, USA
| | - Ishtiaq Qadri
- Department of Pediatrics, University of Colorado Denver, Aurora, CO 80045, USA
| | | | | | - Rachel C. Janssen
- Department of Pediatrics, University of Colorado Denver, Aurora, CO 80045, USA
| | - Jacob E. Friedman
- Department of Pediatrics, University of Colorado Denver, Aurora, CO 80045, USA
- Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, CO 80045, USA
- Corresponding author: University of Colorado Denver, Department of Pediatrics, P.O. Box 6511, MS 8106, Aurora, CO 80045, USA. Tel.: +1 303 724 3983; fax: +1 303 724 3920.
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Abstract
Nonalcoholic fatty liver disease (NAFLD) represents a burgeoning public health concern in westernized nations. The obesity-related disorder is associated with an increased risk of cardiovascular disease, type 2 diabetes and liver failure. Although the underlying pathogenesis of NAFLD is unclear, increasing evidence suggests that excess saturated fatty acids presented to or stored within the liver may play a role in both the development and progression of the disorder. A putative mechanism linking saturated fatty acids to NAFLD may be endoplasmic reticulum (ER) stress. Specifically, excess saturated fatty acids may induce an ER stress response that, if left unabated, can activate stress signaling pathways, cause hepatocyte cell death, and eventually lead to liver dysfunction. In the current review we discuss the involvement of saturated fatty acids in the pathogenesis of NAFLD with particular emphasis on the role of ER stress.
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Affiliation(s)
- Christopher L. Gentile
- Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, CO 80523
| | - Melinda A. Frye
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523
| | - Michael J. Pagliassotti
- Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, CO 80523
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Ishiyama J, Taguchi R, Akasaka Y, Shibata S, Ito M, Nagasawa M, Murakami K. Unsaturated FAs prevent palmitate-induced LOX-1 induction via inhibition of ER stress in macrophages. J Lipid Res 2010; 52:299-307. [PMID: 21078775 PMCID: PMC3023550 DOI: 10.1194/jlr.m007104] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Palmitic acid (PA) upregulates oxidized LDL receptor-1 (LOX-1), a scavenger receptor responsible for uptake of oxidized LDL (oxLDL), and enhances oxLDL uptake in macrophages. However, the precise underlying mechanism remains to be elucidated. PA is known to induce endoplasmic reticulum (ER) stress in various cell types. Therefore, we investigated whether ER stress is involved in PA-induced LOX-1 upregulation. PA induced ER stress, as determined by phosphorylation of PERK, eIF2α, and JNK, as well as induction of CHOP in macrophage-like THP-1 cells. Inhibitors [4-phenylbutyric acid (PBA), sodium tauroursodeoxycholate (TUDCA), and salubrinal] and small interfering RNA (siRNA) for the ER stress response decreased PA-induced LOX-1 upregulation. Thapsigargin, an ER stress inducer, upregulated LOX-1, which was decreased by PBA and TUDCA. We next examined whether unsaturated FAs could counteract the effect of PA. Both oleic acid (OA) and linoleic acid (LA) suppressed PA-induced LOX-1. Activation of the ER stress response observed in the PA-treated cells was markedly attenuated when the cells were cotreated with OA or LA. In addition, OA and LA suppressed thapsigargin-induced LOX-1 upregulation with reduced activation of ER stress markers. Our results indicate that activation of ER stress is involved in PA-induced LOX-1 upregulation in macrophages, and that OA and LA inhibit LOX-1 induction through suppression of ER stress.
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Affiliation(s)
- Junichi Ishiyama
- Discovery Research Laboratories, Kyorin Pharmaceutical Co., Ltd., 2399-1 Nogi-machi, Shimotsuga-gun, Tochigi 329-0114, Japan
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Wanninger J, Neumeier M, Hellerbrand C, Schacherer D, Bauer S, Weiss TS, Huber H, Schäffler A, Aslanidis C, Schölmerich J, Buechler C. Lipid accumulation impairs adiponectin-mediated induction of activin A by increasing TGFbeta in primary human hepatocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1811:626-33. [PMID: 21070865 DOI: 10.1016/j.bbalip.2010.11.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 10/20/2010] [Accepted: 11/02/2010] [Indexed: 12/18/2022]
Abstract
Fatty liver is commonly detected in obesity and has been identified as a risk factor for the progression of hepatic fibrosis in a wide range of liver diseases. Transforming growth factor beta (TGFβ) and activin A, both members of the TGFβ superfamiliy, are central regulators in liver fibrosis and regeneration, and the effect of hepatocyte lipid accumulation on the release of these proteins was studied. Primary human hepatocytes (PHH) were incubated with palmitic acid or oleic acid to increase lipid storage. Whereas activin A and its natural inhibitor follistatin were not affected, TGFβ was 2-fold increased. The hepatoprotective adipokine adiponectin dose-dependently induced activin A while lowering follistatin but did not alter TGFβ. Activin A was markedly reduced in hepatocyte cell lines compared to PHH and was not induced upon adiponectin incubation demonstrating significant differences of primary and transformed cells. In free fatty acid (FFA)-incubated PHH adiponectin-mediated induction of activin A was impaired. Inhibition of TGFβ receptors ALK4/5 and blockage of SMAD3 phosphorylation rescued activin A synthesis in FFA and in TGFβ incubated cells suggesting that FFA inhibit adiponectin activity by inducing TGFβ. To evaluate whether serum levels of activin A and its antagonist are altered in patients with hepatic steatosis, both proteins were measured in the serum of patients with sonographically diagnosed fatty liver and age- and BMI-matched controls. Systemic adiponectin was significantly reduced in patients with fatty liver but activin A and follistatin were not altered. In summary the current data demonstrate that lipid accumulation in hepatocytes induces TGFβ which impairs adiponectin bioactivity, and thereby may contribute to liver injury.
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Affiliation(s)
- Josef Wanninger
- Department of Internal Medicine I, University of Regensburg, Regensburg, Germany
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Saxena NK, Fu PP, Nagalingam A, Wang J, Handy J, Cohen C, Tighiouart M, Sharma D, Anania FA. Adiponectin modulates C-jun N-terminal kinase and mammalian target of rapamycin and inhibits hepatocellular carcinoma. Gastroenterology 2010; 139:1762-73, 1773.e1-5. [PMID: 20637208 PMCID: PMC2967590 DOI: 10.1053/j.gastro.2010.07.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 05/17/2010] [Accepted: 07/08/2010] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Epidemiological studies have shown that obesity is a risk factor for hepatocellular carcinoma (HCC). Lower adiponectin levels are associated with poor prognosis in obese HCC patients, hence it is plausible that adiponectin acts as a negative regulator of HCC. We investigated the effects of adiponectin on HCC development and its molecular mechanisms. METHODS Assays with Huh7 and HepG2 HCC cells were used to examine the signal transduction pathways involved in the protective functions of adiponectin in HCC. These studies were followed by in vivo approaches using HCC xenografts and tumor analysis. Results from in vitro and in vivo findings were corroborated using human HCC tissue microarray and analysis of clinicopathological characteristics. RESULTS Adiponectin increased apoptosis of HCC cells through activation of caspase-3. Adiponectin increased phosphorylation of c-Jun-N-terminal kinase (JNK) and inhibition of c-Jun-N-terminal kinase-phosphorylation inhibited adiponectin-induced apoptosis and caspase-3 activation. Adiponectin increased phosphorylation of 5'-adenosine monophosphate-activated protein kinase and tumor suppressor tuberous sclerosis complex 2 and inhibited mammalian target of rapamycin phosphorylation. Inhibition of 5'-adenosine monophosphate-activated protein kinase phosphorylation not only inhibited adiponectin-induced c-Jun-N-terminal kinase phosphorylation, but also blocked biological effects of adiponectin. Adiponectin substantially reduced liver tumorigenesis in nude mice. Importantly, analysis of adiponectin expression levels in tissue microarray of human HCC patients revealed an inverse correlation of adiponectin expression with tumor size. CONCLUSIONS Adiponectin protects against liver tumorigenesis; its reduced expression is associated with poor prognosis in obese patients with HCC.
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Affiliation(s)
- Neeraj K. Saxena
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta GA 30322,Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta GA 30322,To whom correspondence should be addressed Neeraj K. Saxena, PhD Room 255, 615 Michael Street, Atlanta, Georgia 30322. Telephone: 404 727 5623 Fax: 404 712 2980
| | - Ping P. Fu
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta GA 30322
| | - Arumugam Nagalingam
- Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta GA 30322
| | - Jason Wang
- Department of Pathology, Emory University School of Medicine, Atlanta GA 30322
| | - Jeffrey Handy
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta GA 30322
| | - Cynthia Cohen
- Department of Pathology, Emory University School of Medicine, Atlanta GA 30322
| | - Mourad Tighiouart
- Department of Biostatistics and Bioinformatics, Emory University School of Medicine, Atlanta GA 30322
| | - Dipali Sharma
- Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta GA 30322
| | - Frank A. Anania
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta GA 30322
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